The present invention relates to hydraulic pressure transformers, and, more particularly, to hydraulic pressure transformers having a movable port block interposed between an end cap and a rotating barrel.
Hydraulic pressure transformers are used to transform an input flow of hydraulic fluid at a first flow rate and pressure to an output flow of hydraulic fluid at a second flow rate and pressure. The output flow rate and pressure-are variable to provide a variable output flow and/or variable output pressure to a specific application, such as a cylinder or motor.
Hydraulic pressure transformers may include a housing with a rotatable barrel and a movable port plate disposed therein. The port plate includes three arcuate slots which selectively interconnect a plurality of ports in the housing with a plurality of cylinders in the barrel upon rotation of the barrel during use. The relative position between the slots in the port plate and the ports in the housing define the output pressure from the hydraulic pressure transformer. An example of this type of a hydraulic pressure transformer is disclosed in PCT International Application No. PCT/NL97/00084, published Aug. 28, 1997.
It is also known to provide a hydraulic pressure transformer with a port block instead of a port plate between the housing and barrel. The port block includes a spherical surface on each end thereof which abuts a complimentary spherical surface on the housing and barrel, respectively. The spherical surfaces at each end of the port block allow slight tipping or tilting between the housing, port block and barrel, while at the same time maintaining a substantially sealed relationship therebetween.
A port block as described above is typically rotatably carried within the housing by a pair of large diameter roller bearings which are seated within the housing and radially surround a port block. Both the housing and the port block are usually formed with stepped annular surfaces which are used to properly seat the roller bearing assemblies relative to each of the housing and the port block. The port block includes an annular flange positioned between the stepped annular surfaces which has teeth on the radial periphery thereof. A pinion gear is rotatably carried by the housing and includes teeth which enmesh with the teeth on the annular shoulder of the port block. Rotation of the pinion shaft using a suitable drive in turn effects the proper positioning of the port block within the housing. The pinion shaft, enmeshing gears, roller bearing assemblies, and stepped annular shoulders which are formed to receive the bearing assemblies, increase the manufacturing complexity and cost of the hydraulic pressure transformer. Additionally, the pinion shaft and associated external drive source increase the size of the hydraulic pressure transformer.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the invention, a hydraulic pressure transformer for the conversion of an input hydraulic power to an output hydraulic power comprises an end cap with an opening having a peripheral surface and a first end face. The end cap further includes a plurality of ports opening at the end face and at least one actuation port. A barrel which is rotatable about an axis includes a second end face and a plurality of cylinders having respective cylinder ports which open at the second end face. A port block is disposed within the end cap opening between the first end face of the end cap and the second end face of the barrel. The port block is rotatable about an axis and has a first face surface, a second face surface and a plurality of ports extending between the first face surface and the second face surface. The ports selectively fluidly interconnect the plurality of cylinder ports in the barrel with the plurality of ports in the end cap. The port block includes a radial periphery defining a generally annular channel with the peripheral surface of the opening. The annular channel is disposed in communication with each actuation port. The port block further includes at least one vane extending radially outward from the radial periphery to a position adjacent the peripheral surface of the opening.
In another aspect of the invention, a hydraulic pressure transformer for the conversion of an input hydraulic power to an output hydraulic power comprises an end cap with an opening having a peripheral surface and a first end face. The end cap includes two barrier walls extending radially inward from the peripheral surface. The end cap further includes a plurality of ports opening at the end face and two pairs of actuation ports opening at the peripheral surface. Each pair of actuation ports is disposed adjacent and on opposite sides of a corresponding barrier wall. A barrel which is rotatable about an axis includes a second end face and a plurality of cylinders having respective cylinder ports which open at the second end face. A port block is disposed within the end cap opening between the first end face of the end cap and the second end face of the barrel. The port block is rotatable about an axis and has a first face surface, a second face surface and a plurality of ports extending between the first face surface and the second face surface. The ports selectively fluidly interconnect the plurality of cylinder ports in the barrel with the plurality of ports in the end cap. The port block includes a radial periphery defining a generally annular channel with the peripheral surface of the opening. The port block further includes two vanes extending radially outward from the radial periphery to a position adjacent the peripheral surface of the opening. The vanes are disposed on generally opposite sides of the port block.